U.S. patent application number 10/344673 was filed with the patent office on 2004-02-26 for drive assembly for wind turbines.
Invention is credited to Bogaert, Roger, De Wilde, Marcel, Flamang, Peter.
Application Number | 20040038770 10/344673 |
Document ID | / |
Family ID | 26244839 |
Filed Date | 2004-02-26 |
United States Patent
Application |
20040038770 |
Kind Code |
A1 |
Flamang, Peter ; et
al. |
February 26, 2004 |
Drive assembly for wind turbines
Abstract
A drive assembly for a wind turbine comprises a rotor hub (14),
supporting structure such as a turbine nacelle (15), a planetary
type gear transmission unit (11) comprising sun (27), planet (25)
and ring (24) gears and a planet carrier (28), said ring gear being
non-rotatably secured to said supporting structure (15), a main
bearing (23) which rotatably supports the rotor hub (14) and planet
carrier (28) relative to said ring gear and supporting structure,
and said drive assembly comprising two substantially independent
force transmission paths for transmission of forces reacting with
forces exerted by the wind turbine rotor hub, a first of said force
transmission paths acting from the rotor hub (14) via said main
bearing (23) to the supporting structure (15) primarily for
transmission of overhang load forces and bending moment forces and
a second of said force transmission paths acting front the rotor
hub (14) via said planet carrier (28) primarily for transmission of
rotational forces.
Inventors: |
Flamang, Peter; (Antwerp,
BE) ; De Wilde, Marcel; (Antwerp, BE) ;
Bogaert, Roger; (Antwerp, BE) |
Correspondence
Address: |
YOUNG & THOMPSON
745 SOUTH 23RD STREET 2ND FLOOR
ARLINGTON
VA
22202
|
Family ID: |
26244839 |
Appl. No.: |
10/344673 |
Filed: |
September 4, 2003 |
PCT Filed: |
August 3, 2001 |
PCT NO: |
PCT/IB01/01395 |
Current U.S.
Class: |
475/348 |
Current CPC
Class: |
F03D 15/00 20160501;
F16C 19/386 20130101; F03D 1/00 20130101; F03D 80/70 20160501; Y02E
10/726 20130101; F03D 9/25 20160501; F05B 2260/40311 20130101; Y02E
10/72 20130101; Y02E 10/722 20130101; F16H 2001/289 20130101; Y02E
10/725 20130101; F03D 15/10 20160501 |
Class at
Publication: |
475/348 |
International
Class: |
F16H 057/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 15, 2000 |
GB |
0020014.7 |
Jan 23, 2001 |
GB |
0101715.1 |
Claims
1. A drive assembly for a wind turbine comprising a rotor hub,
supporting structure such as a turbine nacelle, a planetary type
gear transmission unit comprising sun, planet and ring gears and a
planet carrier, said ring gear being non-rotatably secured to said
supporting structure, a main bearing which rotatably supports the
rotor hub and planet carrier relative to said ring gear and
supporting structure, and said drive assembly comprising two
substantially independent force transmission paths for transmission
of forces reacting with forces exerted by the wind turbine rotor
hub, a first of said force transmission paths acting from the rotor
hub via said main bearing to the supporting structure primarily for
transmission of overhang load forces and bending moment forces and
a second of said force transmission paths acting from the rotor hub
via said planet carrier primarily for-transmission of rotational
forces.
2. A drive assembly according to claim 1, wherein, as considered in
an axial direction parallel with the axis of rotation of the planet
carrier, the ring gear is substantially aligned axially with the
main bearing.
3. A drive assembly according to claim 1 or claim 2, wherein the
main bearing comprises an inner ring bearing surface of a diameter
greater than that of the toothed surface of the ring gear.
4. A drive assembly according to any one of the preceding claims,
wherein the sun, planet and ring gears lie in a transverse plane
which contains said main bearing.
5. A drive assembly according to any of the preceding claims,
wherein at all radial positions inwards of the toothed surface of
the ring gear the second force transmission path is substantially
independent of the first force transmission path.
6. A drive assembly according to any of the preceding claims,
wherein the second of said force transmission paths comprises a
radially extending torque transmission member which is torsionally
stiff but relatively compliant in an axial direction parallel with
the axis about which the rotational forces act.
7. A drive assembly according to any one of the preceding claims,
wherein the outer ring of the main bearing is connected or adapted
for connection to a wind turbine rotor hub.
8. A drive assembly according to any one of the preceding claims,
wherein the main bearing and gear transmission unit are of an
integrated construction.
9. A drive assembly according to claim 8 wherein the ring gear
provides a bearing surface for rotatable bearing components of the
main bearing.
10. A drive assembly according to any one of claims 1 to 8, wherein
an inner ring of the main bearing is supported by the ring
gear.
11. A drive assembly according to claim 10, wherein the ring gear
provides axial and radial locations for the main bearing.
12. A drive assembly according to claim 11, wherein the ring gear
has a radially outer surface of a stepped profile to define a
shoulder for axial location of an inner bearing ring of the main
bearing.
13. A drive assembly according to claim 11, wherein the inner
bearing ring is secured axially between said shoulder and said
supporting structure.
14. A drive assembly according to any one of the preceding claims,
wherein the ring gear is provided with a reinforcing ring.
15. A drive assembly according to claim 14, wherein said
reinforcing ring extends axially and or radially beyond the toothed
surface of the ring gear.
16. A drive assembly according to claim 14 or claim 15 when
dependant on claim 12 or claim 13, wherein the reinforcing ring
provides an axial location of the main bearing.
17. A drive assembly according to any one of claims 1 to 9, wherein
the main bearing is mounted on a flange which connects the ring
gear to the supporting structure.
18. A drive assembly according to any one of the preceding claims,
wherein the main bearing comprises a double taper bearing.
19. A drive assembly according to claim 18, wherein the double
taper bearing comprises a single outer bearing ring.
20. A drive assembly according to claim 19, wherein the rotor hub
is rigidly secured relative to said single outer bearing ring.
21. A drive assembly according to any one of claims 18 to 20,
wherein the double taper bearing comprises rollers arranged in an O
configuration in which the rollers of one series increase in
diameter in a direction away from the rollers of the other series
of the pair.
22. A drive assembly according to any one of the preceding claims,
wherein the gear transmission unit is adapted to support an
electrical generator.
23. A drive assembly for a wind turbine according to claim 1, and
substantially as hereinbefore described.
24. A wind turbine comprising rotors, an electrical generator and a
drive assembly according to any one of the preceding claims.
25. A gear transmission unit for use in a wind turbine to transmit
forces from a rotor hub to a generator, said gear transmission unit
comprising a planetary type gear transmission unit comprising sun,
planet and ring gears and a planet carrier, said ring gear being
adapted for non-rotatably securing to supporting structure such as
a turbine nacelle, a main bearing which rotatably supports the
planet carrier and is adapted for rotatably supporting a rotor hub
relative to said ring gear and supporting structure, and said gear
transmission unit comprising two substantially independent force
transmission paths for transmission of forces reacting in use with
forces exerted by the wind turbine rotor hub, a first of said force
transmission paths acting via said main bearing to the supporting
structure primarily for transmission of overhang load forces and
bending moment forces and a second of said force transmission paths
acting via said planet carrier primarily for transmission of
rotational forces.
26. A gear transmission unit according to claim 25, and
substantially as hereinbefore described.
Description
[0001] This invention relates to a drive assembly and to a gear
transmission unit for a wind turbine.
[0002] There is a continuing demand for larger wind turbines
especially for offshore sites due to scarcity of suitable sites and
cost of civil works. At the same time the requirements for
reduction of size and weight of the machines and their components
become more and more important. Typically a wind turbine rotor
drives the low speed shaft of a gear transmission unit, which
transforms torque and speed of the rotor to the required torque and
speed of an electrical generator.
[0003] Integration of the components in a wind turbine is a way to
reduce the weight and to make the drive assembly more compact, but
it is important that the design and execution of the drive assembly
avoids mutual interference of the external and internal loads on
the different components. It is also important that the
construction of an integrated drive assembly allows effective
lubrication to be achieved economically and reliably.
[0004] The present invention seeks to provide an improved drive
assembly and an improved gear transmission unit for a wind turbine
and which permits an advantageous integration of components.
[0005] In accordance with one aspect of the present invention a
drive assembly for a wind turbine comprises a rotor hub supporting
structure such as a turbine nacelle, a planetary type gear
transmission unit comprising sun, planet and ring gears and a
planet carrier, said ring gear being non-rotatably secured to said
supporting structure, a main bearing which rotatably supports the
rotor hub and planet carrier relative to said ring gear and
supporting structure, and said drive assembly comprising two
substantially independent force transmission paths for transmission
of forces reacting with forces exerted by the wind turbine rotor
hub, a first of said force transmission paths acting from the rotor
hub via said main bearing to the supporting structure primarily for
transmission of overhang load forces and bending moment forces and
a second of said force transmission paths acting from the rotor hub
via said planet carrier primarily for transmission of rotational
forces.
[0006] In accordance with another aspect of the present invention a
gear transmission unit for use in a wind turbine to transmit forces
from a rotor hub to a generator comprises a planetary type gear
transmission unit comprising sun, planet and ring gears and a
planet carrier, said ring gear being adapted for non-rotatably
securing to supporting structure such as a turbine nacelle, a main
bearing which rotatably supports the planet carrier and is adapted
for rotatably supporting a rotor hub relative to said ring gear and
supporting structure, and said gear transmission unit comprising
two substantially independent force transmission paths for
transmission of forces reacting in use with forces exerted by the
wind turbine rotor hub, a first of said force transmission paths
acting via said main bearing to the supporting structure primarily
for transmission of overhang load forces and bending moment forces
and a second of said force transmission paths acting via said
planet carrier primarily for transmission of rotational forces.
[0007] Accordingly, the invention teaches that the overhung load
forces and bending moments from the rotor are taken by a bearing
which is directly connected to stationary parts instead of to the
torque transmitting low speed part of the gear unit.
[0008] Preferably, as considered in an axial direction parallel
with the axis of rotation of the planet carrier, said main bearing
lies at a position substantially aligned axially with the axial
position of at least the ring gear of the gear transmission
unit.
[0009] Preferably the sun, planet and ring gears lie in a
transverse plane (perpendicular to the rotation axis of said
rotational forces) which also contains said main bearing.
[0010] Other preferred features are that the main bearing comprises
an inner ring bearing surface of a diameter greater than that of
the toothed surface of the ring gear, and that at all radial
positions inwards of the toothed surface of the ring gear the
second force transmission path is substantially independent of the
first force transmission path.
[0011] It is further preferred that the second of said force
transmission paths comprises a radially extending torque
transmission member which is torsionally stiff but relatively
compliant in an axial direction parallel with the axis about which
the rotational forces act whereby movement of the hub in
consequence of bending forces is accommodated at least in part by
deflection of the torque transmission member. The torque
transmission member thereby isolates the gear transmission unit
from the potentially damaging effects of bending deflections
experienced by the rotor hub relative to the main rotational axis
of the gear transmission unit.
[0012] The present invention accordingly provides, in a further of
its aspects, a drive assembly in which the main rotor bearing and
gear transmission unit for a wind turbine are of an integrated
construction. The wind turbine rotor hub preferably is connected to
the outer ring of the main bearing. The bearing inner ring
preferably is supported by, and may be directly mounted on, the
ring gear of the planetary gear stage, or on a flange which
connects the ring gear to the supporting structure. In an
alternative construction the ring gear may provide a bearing
surface for rotatable bearing components of the main bearing.
[0013] The ring gear may provide axial and radial locations for the
main bearing. The ring gear may have a radially outer surface of a
stepped profile to define a shoulder for axial location of an inner
bearing ring of the main bearing. The inner bearing ring may be
secured axially between said shoulder and said supporting
structure.
[0014] The ring gear may be provided with a reinforcing ring, and
said reinforcing ring may extend axially and or radially beyond the
toothed surface of the ring gear. Said reinforcing ring may provide
an axial location of the main bearing.
[0015] The main bearing may comprise a double taper bearing, and
said double taper bearing may comprise a single outer bearing ring.
The rotor hub may be rigidly secured relative to said single outer
bearing ring. The double taper bearing may comprise rollers
arranged in an O configuration in which the rollers of one series
increase in diameter in a direction away from the rollers of the
other series of the pair.
[0016] In a yet further of its aspects the present invention
provides a wind turbine comprising rotors, a generator and a drive
assembly of a type in accordance with the present invention.
[0017] The gear transmission unit, e.g. a housing thereof, may be
arranged to support an electrical generator.
[0018] Embodiments of the invention will now be described, by way
of example only, with reference to the accompanying diagrammatic
drawings in which:
[0019] FIG. 1 is an elevation view of a wind turbine having a drive
assembly of the present invention;
[0020] FIG. 2 is a sectional view of part of a gear transmission
unit in accordance with the present invention;
[0021] FIG. 3 shows part of FIG. 2 in more detail;
[0022] FIGS. 4, 5 and 6 each show variations of the construction of
FIGS. 2 and 3;
[0023] FIG. 7 shows part of FIG. 6 in more detail, and
[0024] FIGS. 8 and 9 each show further variations of the
construction of FIGS. 2 and 3.
[0025] A wind turbine 10 (see FIG. 1) comprises a gear transmission
unit 11 which acts to transmit torque from rotor blades 12 and
rotor hub 14 to an electrical generator 13, the gear transmission
unit comprising an epicyclic gear unit. The gear transmission unit
and generator are housed in and supported by a nacelle 15.
[0026] The gear transmission unit 11 is now described in more
detail with reference to FIGS. 2 and 3. The gear transmission unit
11 comprises an epicyclic gear unit having four planet gears 25, a
sun gear 27 a planet carrier 28, and a ring gear 24 which is
non-rotatably mounted relative to the nacelle structure 15.
[0027] The sun gear is connected to an output shaft (not shown)
which connects either to a further gear unit or direct to the rotor
of the generator 13.
[0028] The radially outer surface 29 of the ring gear 24 provides
location and support for the inner ring 30 of a main bearing
23.
[0029] The outer ring 31 of the main bearing has secured thereto
the rotor hub 14 and, interposed between the rotor hub and ring 31,
the outer region 22 of the planet carrier 28.
[0030] The planet carrier 28 comprises four bearing support studs
26 uniformly circumferentially spaced to locate bearings 32 which
rotatably support the four planet gears 25. The planet carrier 28
has an annular region 33 which extends radially between the radial
position of the bearing studs 26 and the outer region 22 and is
designed to be relatively stiff, in a circumferential direction
about the Y axis, for transmission of torque between the region 22
and the bearing studs 26, but to be relatively flexible about the X
and Z axis.
[0031] In the aforedescribed construction the torque acting on the
rotor hub 14 under action of the rotor blades 12 is transmitted to
the planet gears 25 via the planet carrier 28 rotatably mounted at
is outer region 22 to the outer ring 31 of bearing 23. Bending
moments and axial forces in the Y direction exerted by the rotor
hub in this construction are transmitted direct to the bearing 23.
The flexibility of the annular portion 33 of the planet carrier 28
assists to substantially isolate those forces from the planet
gears.
[0032] FIG. 4 shows a variation 40 in which the planet carrier 41
is provided with three integral and uniformly circumferentially
spaced studs 42 which support a planet bogie plate 43. The planet
bogie plate 43 provides support for three circumferentially
uniformly spaced shafts 44 arranged each to self adjust in angular
position on the plate 43. Each shaft 44 provides support, at
opposite sides if the plate 43, for a pair of bearings 45, 46 about
which each of a pair of planet gears 47, 48 are rotatably mounted
for engagement with the ring gear 49.
[0033] In a further variation 50, shown in FIG. 5, the planet
carrier 56 is of a cage type design. In this construction each of
three planet bearing support shafts 51 is supported at one axial
end 52 by the part 53 of the planet carrier that extends radially
outwards to be supported by the outer ring of the main bearing 54
whilst the other end 55 is supported by an auxiliary driving plate
57 carried by three circumferentially uniformly spaced supports 58
provided at positions interposed circumferentially between the
shafts 51. The plate 57 is provided with a central aperture 59 to
which an output shaft 60 extends from the sun gear 61.
[0034] FIG. 6 shows a further variation of the construction of
FIGS. 2 and 3. In this construction the planet carrier is
constructed substantially similar to that described with reference
to FIG. 5. However the ring gear 63 differs in so far as part of
the outer periphery of the gear is surrounded by a reinforcing
support ring 64. The reinforcing ring is either formed integrally,
e.g. forge rolled, with the outer ring 63 or permanently secured
thereto, for example by being a shrink fit thereon. The presence of
the support ring, provided axially at a position spaced from the
nacelle structure 15 provides an abutment surface 65 for axial
location of the inner ring of the main bearing 66. The main bearing
66 may be a double taper type bearing, shown in more detail in FIG.
7. The main bearing comprises an inner ring of a split construction
comprising two taper rings 67. The bearing additionally comprises a
single outer ring 68 of double taper form.
[0035] A further variation of the construction of FIGS. 2 and 3 is
shown in FIG. 8. In this construction 80 the inner ring of the main
rotor bearing 81 contrasts with aforedescribed constructions in so
far as it is not directly mounted on or supported by the ring gear
82. Instead, the inner ring of the bearing 81 is supported by a
flange assembly 83 secured to the nacelle structure 15. In the
construction 90 of FIG. 9 the bearing inner ring is connected
substantially directly to the nacelle structure 15 at position
91.
[0036] Whilst the constructions of FIGS. 8 and 9 show that the
inner ring of the main bearing is non-rotatably secured relative to
the nacelle structure 15. it is to be understood that the outer
ring of the main bearing may be secured to the nacelle structure
and that the rotor hub and planet carrier may be rotatably
supported by the inner ring of the bearing.
[0037] In the aforedescribed constructions the sun, planet and ring
gears are all substantially aligned with one another as considered
in an axial direction parallel with the axis of rotation of the
planet carrier. A further feature common to the described
embodiments of the invention is that the main bearing comprises an
inner ring bearing surface the diameter of which is greater than
that of the toothed surface of the ring gear. The substantially
direct attachment of the rotor hub to the main bearing results in
provision of a torque transmission path which at all radial
positions inwards of the toothed surface of the ring gear is
substantially independent of the force transmission path by which
bending and other forces other than those causing rotation about
the rotational axis Y, are transmitted to the nacelle support
structure.
[0038] A benefit arising from the drive assembly, and the gear
transmission unit of the present invention as used in a wind
turbine is that the overhung loads generated by the wind turbine
rotor blades have only a minimal effect on the planet driving
components and on the gear meshing contact of the planetary gear
stage. This allows for an increased power rating of the gear
transmission unit or a reduction of dimension for a given power
rating as compared with hitherto known constructions. It is also to
be appreciated that the forces generated in gear meshing of the
planets have only a minimal effect on the load distribution over
the bearing rollers in the main bearing, thus increasing the load
capacity of the main bearing or allowing for reduction of
dimensions of that bearing for a given load capability.
* * * * *